Container tank

ABSTRACT

A frame type container tank (1) comprises a tank (3) located within the framework (2). Fusto-conical bearer plates (25) mount the tank (3) to end frames (9) of the framework (2) and upper and lower longitudinal members (20, 21) join the end frames (9). Four reinforcing plate members (30) at the four lower corners of the framework (2) each comprise a pair of identical spaced apart parallel reinforcing plates (31) which extend between and are secured to the bearer plates (25) and the lower longitudinal members (21). Reinforcing struts (45) extend between the reinforcing plate members (30) and the lower longitudinal members (21). The provision of the reinforcing plate members (30) in combination with the reinforcing struts (45) provide for significant weight reduction in the framework (2) without loss in carrying capacity of the container tank (1).

The present invention relates to a container tank of the type suitablefor the transportation of liquids, fluids and other materials with fluidlike characteristics, In particular, the invention relates to acontainer tank of the type normally transported on a truck flat, railwaywagon, and container ship.

Such container tanks can be broadly categorised into two types, namely,beam tanks and frame tanks. Beam tanks are container tanks in which atank is located between and secured to a pair of spaced apart end frameslocated at opposite ends of the tank. In such container tanks, the tankforms an essential structural member of the structure of the containertank, and itself forms a load bearing and load carrying strut. A frametank comprises a framework and the tank is located within the framework.The framework, in general, comprises a pair of spaced apart end framesjoined by a plurality of longitudinally extending members, typically,four longitudinal beams extending between the four opposite corners ofthe respective end frames. The tank is located within the framework, andis secured to the framework by suitable mountings. In such frame tanks,in general, the tank does not form a structural member of the framework,and where it does, plays a relatively insignificant role in the strengthof the framework. Because of the fact that in such frame tanks, theentire load carrying and load bearing capacities must be provided by theframework, the structural members of the framework, and in particular,the longitudinal members extending between the end frames must be ofrelatively high load bearing and carrying capacity to withstand staticstresses which are induced in the framework by its own weight, theweight of the tank and the weight of the contents of the tank, and alsoto withstand dynamic stresses, which are induced in the framework duringtransportation. Such dynamic stresses can result from rapid accelerationand deceleration, as well as centrifugal forces resulting fromtransportation of the tank. Indeed, such dynamic forces may not alwaysact directly longitudinally or transversely of the tank, they may act onthe framework at an angle, thus tending to induce buckling stresses andstrains in the framework. To provide the necessary load bearing andcarrying capacities and to withstand such stresses, in general, thelongitudinal members extending between the end frames must be providedby I-beams of relatively large transverse cross section. Such I-beamstend to be relatively heavy, and significantly increase the weight ofthe framework. In general, container tanks are subject to maximumoverall fully laden weights stipulated by road, rail, shipping and otherfreight transport authorities. Thus, any increase in the weight of theframework for structural purposes or otherwise leads to a reduction inthe carrying capacity of the container tank.

There is therefore a need for a container tank of the frame type inwhich the weight of the framework can be reduced, particularly, by theprovision of longitudinal members extending between the end frames ofrelatively lighter weight than is required in frame tanks knownheretofore.

The present invention is directed towards providing such a containertank.

According to the invention, there is provided a container tankcomprising an elongated tank defining a longitudinally extending centralaxis, and defining four quadrants in transverse cross section, namely, apair of upper quadrants and a pair of lower quadrants, the tank beingdisposed between a pair of spaced apart end frames extendingtransversely of the central axis at respective opposite ends of thetank, the end frames being joined by a pair of spaced apart parallellower longitudinal members extending from positions adjacent respectiveopposite lower corners of the end frames, and a mounting means at eachend of the tank for mounting the tank to the adjacent end frame, whereineach mounting means comprises at least one bearer plate extending fromthe tank adjacent the lower quadrants thereof to the adjacent end frame,and each bearer plate is secured to the tank and the adjacent end frame,and four reinforcing plate members are located adjacent the fourrespective lower corners of the end frames, each reinforcing platemember extending between and being secured to the adjacent lowerlongitudinal member and the bearer plate.

Preferably, each reinforcing plate member is secured to the adjacent endframe. Advantageously, each reinforcing plate member extends from theadjacent bearer plate and is secured to an adjacent portion of the tank.

Ideally, an elongated reinforcing strut is secured to each reinforcingplate member at a position adjacent the bearer plate and spaced apartfrom the lower longitudinal member, each reinforcing strut extendingfrom the adjacent reinforcing plate member towards the adjacent lowerlongitudinal member and being secured to the lower longitudinal memberat a position spaced apart from the adjacent reinforcing plate member.

In one aspect of the invention, a portion of a peripheral edge of eachreinforcing plate member intermediate the adjacent lower longitudinalmember and the reinforcing strut defines an arcuate recess, the adjacentlower longitudinal member and reinforcing strut extending from thereinforcing plate member tangentially to the arcuate peripheral edgeportion.

Preferably, each reinforcing plate member comprises a pair of spacedapart parallel reinforcing plates, the reinforcing plates of eachreinforcing plate member being secured to opposite sides of the adjacentlower longitudinal member. Advantageously, each reinforcing plate isprovided with an arcuate peripheral edge portion intermediate theadjacent lower longitudinal member and the adjacent reinforcing strut.Ideally, an arcuate connecting plate extends between the reinforcingplates of each reinforcing plate member adjacent the arcuate peripheraledge portions of the respective reinforcing plates, the connecting plateco-inciding with the arcuate peripheral edge portions.

Each reinforcing plate member defines a central plane parallel to thereinforcing plates the central plane containing the central axis of thetank, and preferably, the central plane of each reinforcing plate memberextends downwardly from the central axis of the tank at an angle to thevertical in the range of 30° to 60°. Advantageously, the central planeof each reinforcing plate member extends downwardly from the centralaxis of the tank at an angle to the vertical of approximately 45°.Ideally, the lower longitudinal member and the reinforcing strutadjacent each reinforcing plate member lie in the central plane of thereinforcing plate member.

It is preferable that the two reinforcing struts adjacent each lowerlongitudinal member are secured to the lower longitudinal member atspaced apart locations. Preferably, the two respective reinforcingstruts extend to and are secured to the lower longitudinal member atlocations short of the midway position between the respective ends ofthe lower longitudinal member. Advantageously, the two respectivereinforcing struts are secured to the lower longitudinal member atlocations equi-spaced on opposite sides of the midway position. Ideally,the two reinforcing struts adjacent each lower longitudinal member aresecured to the lower longitudinal member by an elongated connectingmember of U-shaped cross section, the connecting member having a pair ofspaced apart side webs extending from a main transverse web, the sidewebs being secured to the lower longitudinal member and defining withthe main web and the lower longitudinal member an elongated bore forreceiving the respective reinforcing struts.

In one embodiment of the invention, the tank comprises an elongatedcentral shell defining the central axis, the ends of the central shellbeing closed by a pair of transversely extending end caps. Preferably,each bearer plate extends from the tank adjacent the central shell.Advantageously, each bearer plate extends from the central shell of thetank adjacent the adjacent end cap thereof.

In another embodiment of the invention, the tank is of circulartransverse cross section.

It is preferable that each bearer plate is an arcuate bearer plate, andeach bearer plate defines an axis of generation extending generallyparallel to the central axis of the tank. Preferably, each bearer plateis formed by portion of a conical wall which diverges away from thetank. Advantageously, the bearer plate at each end of the tank extendscompletely around the tank and defines an axis of generation co-incidingwith the central axis of the tank. Ideally, the curvature of each bearerplate adjacent the tank co-incides with the curvature of the centralshell of the tank.

In another embodiment of the invention, each end frame comprises a pairof spaced apart upstanding side members joined by spaced apart top andbottom cross members. Preferably, each bearer plate is secured to theside and top and bottom cross members of the end frame. Preferably, eachreinforcing plate member is secured to the adjacent lower longitudinalmember of the bearer plate and the reinforcing strut by seam welding,and preferably, each bearer plate is secured to the tank and the endframe by seam welding.

In one aspect of the invention, a pair of spaced apart parallel upperlongitudinal members extend from positions adjacent respective oppositeupper corners of the end frame for forming with the end frames and thelower longitudinal members a framework within which the tank is located.

The advantages of the invention are many. A particularly importantadvantage of the invention is that it facilitates the provision of aframe type container tank in which the overall weight of the frame issubstantially less than frames of container tanks known heretofore for asimilar load carrying and bearing capacity. In particular, the containertank according to the invention is provided with longitudinal membersextending between the end frames of cross section considerably less thanwould be required in a frame type tank known heretofore, and since thecross section of longitudinal members is less than those knownheretofore, likewise, the weight of the longitudinal members is likewiseless than the weight of longitudinal members required for frame typetanks known heretofore. Accordingly, the invention facilitates theprovision of a frame type tank of considerably less weight for the sameload bearing and carrying capacity of tanks known heretofore. As well asthe load bearing and carrying capacities of the container tank accordingto the invention being substantially similar to that of known tankswhile the overall weight of the frame is significantly reduced, it hasalso been found that there is a significant improvement in the fatiguecharacteristics of the tank. In other words, the possibility of failureof the container tank resulting from fatigue is considerably less thanwould normally be expected. These advantages are largely achieved by theprovision of the four reinforcing plate members located adjacent thelower corners of the end frame in combination with the fact that thereinforcing plate members are secured to the bearer plates adjacent thelower quadrants of the tank and to the lower longitudinal members. Theprovision of reinforcing struts also, it has been found, significantlyincreases the load carrying and load bearing capacity of the containertank. It has also been found that as well as being able to withstandstatic loads, the container tank according to the invention isparticularly strong and well capable of withstanding dynamic stressesand stains. In particular, the provision of the reinforcing platemembers extending between and secured to the bearer plates and the lowerlongitudinal members considerably strengthens the frame, and in turn,the container tank against buckling which would otherwise result fromnon-axially applied forces to the framework. Additionally, the provisionof the reinforcing struts coupled with the reinforcing plate memberssubstantially eliminates any danger of bowing of the lower longitudinalmembers, thereby further preventing buckling of the framework of thecontainer tank.

It is believed that these and many other advantages of the containertank of the invention are achieved by virtue of the fact that the tankforms an integral structural load bearing and load carrying member ofthe framework. This is firstly achieved by virtue of the fact that thetank is secured to the framework by bearer plates extending at oppositeends of the tank to the adjacent end frames. Secondly, by virtue of thefact that the four reinforcing plate members are provided extendingbetween and secured to the lower longitudinal members and the bearerplates, the tank is rigidly secured to and anchored in the framework,and buckling of the framework is resisted.

By virtue of the fact that the bearer plates are of fusto-conical shape,the bearer plates engage the end frames adjacent the periphery of theend frames, thereby enabling the end frames to be provided of lighterweight material without reducing the load bearing and load carryingcapacity of the framework and the container tank.

The invention will be more clearly understood from the followingdescription of a preferred embodiment thereof, which is given by way ofexample only, with reference to the accompanying drawings in which:

FIG. 1 is a side elevational view of a container tank according to theinvention,

FIG. 2 is an end elevational view of the container tank of FIG. 1,

FIG. 3 is a top plan view of portion of the container tank of FIG. 1,

FIG. 4 is a true plan view of portion of the container tank of FIG. 1viewed in the direction of the arrow A of FIG. 2,

FIG. 5 is a perspective view of portion of the container tank of FIG. 1,

FIG. 6 is a perspective view of a detail of the container tank of FIG.1,

FIG. 7 is a true plan view of the detail of FIG. 6 in the direction ofthe arrow A of FIG. 2,

FIG. 8 is a cross sectional view of the detail of FIG. 6 on the lineVIII--VIII of FIG. 6,

FIG. 9 is a cross sectional view of the detail of FIG. 6 on the lineIX--IX of FIG. 4, and

FIG. 10 is a cross sectional view of another detail of the containertank of FIG. 1 on the line X--X of FIG. 4.

Referring to the drawings, there is illustrated a container tankaccording to the invention indicated generally by the referencenumeral 1. The container tank 1 in this case is of the frame tank typeand is particularly suitable for the transportation of liquids, gas andother materials with fluid like characteristics. The container tank 1comprises a framework 2 and an elongated tank 3 for the liquid locatedwithin and mounted to the framework 2. The tank 3 may be of steel,stainless steel or any other suitable material depending on the contentsto be carried in the tank 3. The tank 3 comprises an elongated centralcylindrical shell 5 which defines a longitudinally extending centralaxis 6, and four quadrants 7, namely, two upper quadrants 7a and twolower quadrants 7b. A pair of end caps 8 seam welded to the cylindricalshell 5 close the ends of the shell 5. The thickness of the material ofthe shell 5 and end caps 8 will be determined largely by the materialfrom which the tank 3 is constructed, and also by the type of liquid orother materials to be transported in the tank 3. Hand and manholescovered by lids, as well as inlet and outlet pipes and valves, areprovided to the tank 3, but are not illustrated. The provision of suchdetails in tanks of container tanks will be well known to those skilledin the art.

The framework 2 comprises a pair of end frames 9 which extendtransversely of the central axis 6 at the respective ends of the tank 3.The end frames 9 comprise a pair of upright side members 10 joined bytop and bottom cross members 11 and 12, respectively. The side, top andbottom cross members 10, 11 and 12, are of box section steel, in thiscase, the side members 10 are of 150 mm by 150 mm external transversecross section. The top cross members 11 are of 100 mm by 100 mm externaltransverse cross section. The bottom cross members 12 are of 150 mm by100 mm external transverse cross section. The side, top and bottom crossmembers 10, 11 and 12, respectively, are joined together by four cornercastings 14 of the type manufactured to ISO standards which will be wellknown to those skilled in the art, and which are suitable for securelyengaging the container tank 1 on a truck flat, stacking a plurality ofcontainer tanks one on top of the other, and for connection to a liftingframe of a hoist and the like. The corner castings 14 are welded to theside, top and bottom cross members 10, 11 and 12, respectively. Twoupper and two lower connecting struts 15 also of box section steel 150mm by 100 mm external transverse cross section extend between and arewelded to the side members 10 and the respective top and bottom crossmembers 11 and 12. The end frames 9 are joined by a pair of parallelupper longitudinal members 20 and a pair of lower longitudinal members21 both of box section steel of 100 mm by 100 mm external transversecross section. The upper longitudinal members 20 extend between therespective opposite upper corners of the end frames 9 and are welded tothe upper corner castings 14. Strengthening members 22 of box sectionsteel of 100 mm by 50 mm external transverse cross section extend fromthe top cross member 11 of each end frame 9 to the upper longitudinalmembers 20. The lower longitudinal members 21 are welded to the sidemembers 10 adjacent the lower corner castings 14, and the lowerlongitudinal members 21 are angled as will be described below. Beforedescribing the lower longitudinal members 21 in further detail, themounting of the tank 3 in the framework 2 will first be described.

A mounting means for mounting each end of the tank 3 to the adjacent endframe 9 comprises a bearer plate 25 of steel plate material of 3 mmthickness. Each bearer plate 25 is located at its corresponding end ofthe tank 3 and extends to the adjacent end frame 9. In this example,each bearer plate 25 is of fusto-conical shape, and extends completelyaround the corresponding end of the tank 3, and defines an axis ofgeneration which co-incides with the central axis 6 of the central shell5 of the tank 3. Each bearer plate 25 is seam welded to the centralshell 5 of the tank 3 adjacent the corresponding end cap 8 along acontinuous seam weld 26. The curvature of each bearer plate 25 at theseam weld 26 is substantially similar to the curvature of the centralshell 5 along the seam weld 26. In other words, the diameter of thebearer plates 25 where they join the central shell 5 of the tank 3 issubstantially similar to the diameter of the central shell 5. Eachbearer plate 25 diverges from the tank 3 to the adjacent end frame 9.The bearer plates 25 are seam welded to the side members 10 and the topand bottom cross members 11 and 12, respectively, and to the connectingstruts 15 by continuous seam welds 27. Portions 29 of the bearer plates25 are flattened at each side of the container tank 1 adjacent the sidemembers 10 to avoid the bearer plates 25 extending on either side of thecontainer tank 1 beyond the side members 10.

Four reinforcing plate members 30 are located adjacent the lower cornersof the end frames 9 and extend between and are secured to the adjacentlower longitudinal member 21 and the bearer plate 25 adjacent the lowerquadrants 7b of the tank 3 for strengthening the framework 2 and morerigidly securing the tank 3 in the framework 2. In this way, the tank 3forms a load bearing structural member of the framework 2, therebyenabling a reduction in the load carrying and bearing capacities, and inturn, the weight of the upper and lower longitudinal members 20 and 21.Each reinforcing plate member 30 comprises a pair of parallel spacedapart identical reinforcing plates 31 of steel plate material of 2 mmthick which extend over and sandwich the adjacent lower longitudinalmember 21 therebetween. Each reinforcing plate member 30 comprises amounting plate 32 of steel plate material of 8 mm thickness whichextends along and joins adjacent outer end edges 33 of the reinforcingplates 31. The mounting plate 32 is seam welded to the reinforcingplates 31 along the outer end edges 33. The mounting plate 32 and outerend edges 33 of the reinforcing plates 31 are welded to the side members10 and connecting struts 15 of the adjacent end frame 9. Inner end edges34 of the reinforcing plates 31 are formed with an arcuate peripheraledge portion 35 which defines a recess which is slightly greater than asemi-circular recess. An arcuate connecting plate 38 of steel platematerial of 8 mm thickness extends between the arcuate edges 35 of thereinforcing plates 31, and is seam welded along the arcuate edges 35 tothe respective reinforcing plates 31. Outer side edges 40 of the pairsof reinforcing plates 31 of each reinforcing plate member 30 extend onrespective opposite sides of the adjacent lower longitudinal member 21and are seam welded thereto, thereby sandwiching the lower longitudinalmember 21 between the reinforcing plates 31. Inner side edges 42 of thereinforcing plates 31 are continuously seam welded to the adjacentportion of the bearer plate 25. A portion 43 of each reinforcing plate31 extends beyond the adjacent bearer plate 25, and extends along theshell 5 of the tank 3 and is seam welded to the tank 3 along a seam weld44.

Four reinforcing struts 45 extend from the respective reinforcing platemembers 30 from the portions 43 which are located adjacent the tank 3and thus are spaced apart from the lower longitudinal members 21. Eachreinforcing strut 45 extends from its adjacent reinforcing plate member30 towards the adjacent longitudinal member 21, and is secured theretoby an elongated U-shaped connecting member 47. The end of eachreinforcing strut 45 adjacent the reinforcing plate member 30 issandwiched between the reinforcing plates 31 and is welded to theportions 43. The radius and the shape of the arcuate edges 35 of thereinforcing plates 31 is such that the lower longitudinal member 21 andthe reinforcing strut 45 extend from each reinforcing plate member 30substantially tangentially to the arcuate edges 35 of the reinforcingplates 31. By virtue of the fact that each reinforcing strut 45converges towards the adjacent lower longitudinal member 21, thecurvature of the arcuate edges 35 is such that the arcuate edges 35define a recess which is just more than a semi-circle so that both thereinforcing strut 45 and the lower longitudinal member 21 extendtangentially from the arcuate edges 35. By virtue of the fact that thereinforcing plates 31 are seam welded to the mounting plate 32, theconnecting plate 38, the lower longitudinal member 21, the reinforcingstrut 45 and are seam welded along the bearer plate 25 and portion ofthe shell 5 of the tank 3, the space between the reinforcing plates 31is substantially sealed.

The connecting members 47 comprise a pair of side webs 48 extending froma main transverse web 49. The side webs 48 are seam welded to the lowerlongitudinal members 21 and define with the lower longitudinal member 21and the main web 49 an elongated bore 50 within which the tworeinforcing struts 45 extend. The reinforcing struts 45 join the lowerlongitudinal members 21 at a position just short of the midway position51 between the ends of the lower longitudinal members 21, and thepositions at which two reinforcing struts 45 join their adjacentlongitudinal member 21 are equi-spaced on either side of the midwayposition of the lower longitudinal member 21. The reinforcing struts 45are securely welded to the lower longitudinal members 21 and to theconnecting members 47.

The reinforcing plate members 30 each define a central plane 52 whichextends midway between the reinforcing plates 31 and parallel to thereinforcing plates 31. The two reinforcing plate members 30 on the sameside of the container tank 1 share a common central plane 52. Eachcentral plane 52 contains the central axis 6 and extends from thecentral axis 6 at an angle of approximately 45° to the vertical, seeFIG. 2. Each lower longitudinal member 21 is angled, and itscorresponding reinforcing struts 45 are also angled to co-incide withthe central plane 52 of the corresponding reinforcing plate members 30.

In use, the container tank 1 with the tank 3 full or empty istransported by road, rail, sea or air. The container tank 1 is placed ona truck flat or other platform or support with the lower corner castings14 of the end frames 9 resting on the truck, platform or indeed on theupper corner castings of a lower container tank or other container.

While the container tank has been described as being provided with upperlongitudinal members joining the end frames, the upper longitudinalmembers may in certain cases be dispensed with. It is also envisaged incertain cases that the reinforcing struts may be omitted, and wherereinforcing struts are provided, other suitable means for joining thereinforcing struts to the lower longitudinal members may be providedbesides the U-shaped connecting member, indeed, the connecting membersmay be dispensed with. While the reinforcing plate members have beendescribed as comprising pairs of reinforcing plates, in certain cases,it is envisaged that each reinforcing plate member may comprise only onesingle reinforcing plate.

While a particular construction of end frame and tank has beendescribed, other constructions may be provided. Indeed, it will beappreciated that it is not necessary for the central shell of the tankto be cylindrical, it may be of any other cross section, for example,ovoid, elliptical or the like. In general, it is envisaged that thecurvature of the bearer plates adjacent the tank would be such as tofollow the curvature of the tank.

Needless to say, it will be appreciated that bearer plates ofconstruction and shape other than those described may be provided.Indeed, it will be appreciated that it is not essential for the bearerplates to be of fusto-conical shape, and it is also not essential thatthe bearer plates be flattened on opposite sides of the container tank.Further, it will be appreciated that instead of providing a singlebearer plate at each end of the tank, the bearer plate may be providedin a number of segments which would be separated from each otherextending from the end of the tanks to the end frames. For example, apair of bearer plates may be provided at each end of the tank, onebearer plate would be almost semi-circular and extend from the top ofthe tank to the end frame, while the other would likewise be almostsemi-circular and would extend from the bottom portion of the tank tothe end frame. It is also envisaged that in certain cases the bearerplate may only extend from the lower quadrants of the tank to the endframe adjacent the reinforcing plate members, and in certain cases, twobearer plates may be provided, one associated with a correspondingreinforcing plate member. In such cases, other suitable mounting meansbesides bearer plates may be provided at the upper portion of the tank.

While the upper and lower longitudinal members and the reinforcingstruts have been described as being of box section steel, they may be ofany other cross section, and of any other suitable material. Forexample, they may be of circular cross section, channel cross section,I-cross section, T-cross section, angle cross section or the like. Wherethey are of circular cross section they may be of solid or hollowsection. Additionally, the cross section of these members may bedifferent. Needless to say, the above cross sections are given by way ofexample only, and many other cross sections may be used. The material ofthe upper and lower longitudinal members and reinforcing struts may bealuminium, stainless steel, alloy or the like. Additionally, it will beappreciated that the material of the bearer plates and reinforcingplates, the mounting plates and the connecting plate may be of any othersuitable material besides steel, for example, aluminium, stainlesssteel, or alloy.

It will also be appreciated that the end frames may be of any othersuitable material besides steel, and the side, top and bottom crossmembers may be of any other suitable or desired section besides boxsection.

I claim:
 1. A container tank (1) comprising an elongated tank (3)defining a longitudinally extending central axis (6), and defining fourquadrants (7) in transverse cross section, namely, a pair of upperquadrants (7a) and a pair of lower quadrants (7b), the tank (3) beingdisposed between a pair of spaced apart end frames (9), having oppositelower corners, extending transversely of the central axis (6) atrespective opposite ends of the tank (3), the end frames (9) beingjoined by a pair of spaced apart parallel lower longitudinal members(21) extending from positions adjacent respective opposite lower corners(14) of the end frames (9), and a mounting means (25) at each end of thetank (3) for mounting the tank (3) to the adjacent end frame (9), eachmounting means (25) comprising at least one bearer plate (25) extendingfrom the tank (3) adjacent the lower quadrants (7b) thereof to theadjacent end frame (9), and each bearer plate (25) being secureddirectly to the tank (3) and directly to the adjacent end frame (9),characterised in that four reinforcing plate members (30) are locatedadjacent the four respective lower corners (14) of the end frames, eachreinforcing plate member (30) extending between and being secured to theadjacent lower longitudinal member (21) and the bearer plate (25).
 2. Acontainer tank as claimed in claim 1 characterised in that eachreinforcing plate member (30) is secured to the adjacent end frame (9).3. A container tank as claimed in claim 1 or 2 characterised in thateach reinforcing plate member (30) extends from the adjacent bearerplate (25) and is secured to an adjacent portion of the tank (3).
 4. Acontainer tank as claimed in claim 1 characterised in that an elongatedreinforcing strut (45) is secured to each reinforcing plate member (30)at a position adjacent the bearer plate (25) and spaced apart from thelower longitudinal member (21), each reinforcing strut (45) extendingfrom the adjacent reinforcing plate member (30) towards the adjacentlower longitudinal member (21) and being secured to the lowerlongitudinal member (21) at a position spaced apart from the adjacentreinforcing plate member (30).
 5. A container tank as claimed in claim 4characterised in that each reinforcing plate member (30) defines acentral plane (52) parallel to the reinforcing plates (31), the centralplane (52) containing the central axis (6) of the tank (3).
 6. Acontainer tank as claimed in claim 5 characterised in that the centralplane (52) of each reinforcing plate member (30) extends downwardly fromthe central axis (6) of the tank (3) at an angle to the vertical in therange of 30° to 60°.
 7. A container tank as claimed in claim 6characterised in that the central plane (52) of each reinforcing platemember (30) extends downwardly from the central axis (6) of the tank (3)at an angle to the vertical of approximately 45°.
 8. A container tank asclaimed claim 5 characterised in that the lower longitudinal member (21)and the reinforcing strut (45) adjacent each reinforcing plate member(30) lie in the central plane (52) of the reinforcing plate member (30).9. A container tank as claimed in claim 4 characterised in that the tworeinforcing struts (45) adjacent each lower longitudinal member (21) aresecured to the lower longitudinal member (21) at spaced apart locationsshort of the midway position (51) between the respective ends of thelower longitudinal member (21).
 10. A container tank as claimed in claim9 characterised in that the two respective reinforcing struts (45) aresecured to the lower longitudinal member (21) at locations equi-spacedon opposite sides of the midway position (51).
 11. A container asclaimed in claim 9 characterised in that the two reinforcing struts (45)adjacent each lower longitudinal member (21) are secured to the lowerlongitudinal member (21) by an elongated connecting member (47) ofU-shaped cross section, the connecting member (47) having a pair ofspaced apart side webs (48) extending from a main transverse web (49),the side webs (48) being secured to the lower longitudinal member (21)and defining with the main web (49) and the lower longitudinal member(21) an elongated bore (50) for receiving the respective reinforcingstruts (45).
 12. A container tank as claimed in claim 4 characterised inthat a portion (35) of a peripheral edge (34) of each reinforcing platemember (30) intermediate the adjacent lower longitudinal member (21) andthe reinforcing strut (45) defines an arcuate recess, the adjacent lowerlongitudinal member (21) and reinforcing strut (45) extending from thereinforcing plate member (30) tangentially to the arcuate peripheraledge portion (35).
 13. A container tank as claimed in claim 1characterised in that each reinforcing plate member (30) comprises apair of spaced apart parallel reinforcing plates (31), the reinforcingplates (31) of each reinforcing plate member (30) being secured toopposite sides of the adjacent lower longitudinal member (21).
 14. Acontainer tank as claimed in claim 1 characterised in that eachreinforcing plate (31) is provided with an arcuate peripheral edgeportion (35) intermediate the adjacent lower longitudinal member (21)and the adjacent reinforcing strut (45).
 15. A container tank as claimedin claim 14 characterised in that an arcuate connecting plate (38)extends between the reinforcing plates (31) of each reinforcing platemember (30) adjacent the arcuate peripheral edge portions (35) of therespective reinforcing plates (31), the connecting plate (38)co-inciding with the arcuate peripheral edge portions (35).
 16. Acontainer tank as claimed in claim 1 characterised in that the tank (3)comprises an elongated central shell (5) defining the central axis (6),the ends of the central shell (5) being closed by a pair of transverselyextending end caps (8), each bearer plate (25) extending from thecentral shell (5) of the tank (3) adjacent the adjacent end cap (8)thereof.
 17. A container tank as claimed in claim 1 characterised inthat each bearer plate (25) is an arcuate bearer plate (25), and eachbearer plate (25) defines an axis of generation extending generallyparallel to the central axis (6) of the tank (3).
 18. A container tankas claimed in claim 17 characterised in that each bearer plate (25) isformed by portion of a conical wall (25) which diverges away from thetank (3).
 19. A container tank as claimed in claim 17 characterised inthat the bearer plate (25) at each end of the tank (3) extendscompletely around the tank (3) and defines an axis of generationco-inciding with the central axis (6) of the tank (3) and the curvatureof each bearer plate (25) adjacent the tank (3) co-incides with thecurvature of the central shell (5) of the tank (3).